The application of carbon fibre aircraft seats to permit high strength lightweight structures brings obvious advantages. For lightness it is desirable to form such components as the legs and the seat supports as load-bearing shell structures with carbon fibre reinforced inner layers and an aromatic polyamide fibre reinforced outer layer to impart the necessary mechanical properties such as abrasion resistance and fracture toughness. But it has not hitherto been clear how such structures can be applied to a modern spar type aircraft seat as illustrated, for example, in UK Patent Application No. 2022403 (Aircraft Furnishing Limited) to produce a sufficiently strong structure to withstand normal working loads and the crash stress loads demanded by aircraft certification bodies.